Abstract
The reaction of NO2 with perfluoropropene (C3F6) has been studied at 413.1, 421.0 and 432.8K, using a conventional static system. The initial pressure of NO2 was varied between 43.6 and 204.0Torr and that of C3F6 between 10.2 and 108.5Torr. Several experiments were made adding CF4, varying its pressure from 338.8 to 433.6Torr. Four products were observed: NO and perfluoropropene oxide (PFPO), formed in equivalent amounts, CF3CF(NO2)CF2NO2 and CF3C(O)CF2NO2. The relation R=[PFPO]/([CF3CF(NO2)CF2NO2] + [CF3C(O)CF2NO2]) increases with temperature and decreases as the concentration of NO2 and the total pressure M increase. The yields of PFPO, based on the amount of C3F6 consumed, varied between 63 and 89% and those of CF3CF(NO2)CF2NO2 between 0.33 and 0.08%. Increasing the temperature, the yields of CF3C(O)CF2NO2 decreased from 0.04 to 0.01%. The reaction is homogenous and the consumption rate of perfluoropropene, −d[C3F6]/dt= k
1[C3F6][NO2], is independent of the total pressure. The following mechanism is postulated to explain the experimental results: 1) C3F6 + NO2 → CF3C•FCF2NO2, 2) CF3C•FCF2NO2 → PFPO+NO, 3) CF3C•FCF2NO2 + NO2+M → CF3CF(NO2)CF2NO2+M, 4) CF3C•FCF2NO2 + NO2 → CF3C(O)CF2NO2+FNO. k
1=(4.57±1.4)×106exp(−(15.44±1.2) kcal mol−1/RT) dm3mol−1s−1. The value of k
2, the rate constant for the unimolecular dissociation of the radical CF3C•FCF2NO2, was found to be of order of 1014s−1.
摘要:研究了NO
2与
全氟丙烯(C
3F
6)在413.1、421.0和432.8K下的反应,采用传统的静态系统。NO
2的初始压力在43.6至204.0Torr之间变化,C
3F
6的压力在10.2至108.5Torr之间变化。进行了几次实验,添加了CF
4,将其压力从338.8至433.6Torr之间变化。观察到四种产物:NO和
全氟丙烯氧化物(
PFPO),它们的数量相等,CF
3CF(NO
2)CF
2NO
2和CF
3C(O)CF
2NO
2。关系
R=[
PFPO]/([CF
3CF(NO
2)CF
2NO
2]+[CF
3C(O)CF
2NO
2])随着温度的升高而增加,随着NO
2和总压力M的浓度增加而减小。基于消耗的C
3F
6的数量,
PFPO的产率在63%至89%之间变化,CF
3CF(NO
2)CF
2NO
2的产率在0.33%至0.08%之间变化。随着温度的升高,CF
3C(O)CF
2NO
2的产率从0.04降至0.01%。反应是均相的,
全氟丙烯的消耗速率,−d[C
3F
6]/d
t=
k1[C
3F
6][NO
2],独立于总压力。提出以下机理来解释实验结果:1)C
3F
6+NO
2→CF
3C
•FCF
2NO
2,2)CF
3C
•FCF
2NO
2→
PFPO+NO,3)CF
3C
•FCF
2NO
2+NO
2+M→CF
3CF(NO
2)CF
2NO
2+M,4)CF
3C
•FCF
2NO
2+NO
2→CF
3C(O)CF
2NO
2+FNO。
k1=(4.57±1.4)×10
6exp(−(15.44±1.2) kcal mol
−1/
RT) dm
3mol
−1s
−1。发现
k2,自由基CF
3C
•FCF
2NO
2的单分子解离速率常数,约为10
14s
−1。